JP2002131595A - Protection pipe for chemical resistant optical fiber - Google Patents

Abstract

(57) [Summary] (Modified) [Problem] To lay an optical fiber core wire or a tape core wire in a sewer pipe, exhibit chemical resistance (mainly sulfuric acid resistance), and degrade the poor environment in the sewer pipe. Provided is an optical fiber protection pipe capable of maintaining high tensile strength and bending characteristics even underneath. A protection pipe for a chemical-resistant optical fiber core wire, wherein a multifilamentary tensile fiber 3 is drawn through a molten polyolefin resin from a round nozzle. Alternatively, a protective pipe for a chemical-resistant optical fiber having a reinforcing rib 4 provided on the outside of the pipe in the same direction as the fiber direction. Alternatively, a protective pipe for a chemical-resistant optical fiber coated with a braid of multifilament fiber on the outside of the pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe capable of protecting a tightly bent portion in a sewer pipe and a core (optical fiber) even under an acidic environment.

[0002]

2. Description of the Related Art A conventional optical fiber cable has not been passed through a sewer pipe as it is. that is,
The resin coated on the core wire is acrylic, epoxy, polyamide, soft PVC, etc., while the environment inside the sewer pipe contains acidic liquids and corrosive gases such as hydrogen sulfide, so the optical fiber core This is because the wire coating is destroyed, and the life of the optical fiber is significantly shortened.

[0003]

In recent years, sewage pipes have begun to attract attention as pipelines that are least affected by natural disasters such as earthquakes, typhoons, and lightning strikes.
For this reason, it is preferable to lay an optical fiber to each home using a sewer pipe, from the viewpoint of avoiding risks. However, since there is an acidic liquid or corrosive gas such as hydrogen sulfide in the sewer pipe, it is resistant. Fiber optic cables that have chemical properties and high mechanical strength (tensile strength) are required. As a result, very expensive fiber optic cables must be used, and the development of the communication infrastructure will not proceed. For this reason, there is a need for a low-cost one that protects an optical fiber core and that is easy to lay.

[0004] If the trunk line of the sewage system can be inserted by an operator, there are naturally many straight sections, and it is easy to lay hundreds of acid-resistant optical fiber cables that can control bending and external stress which are disadvantages of optical fibers. However, the main pipe that extends from there, where people can not enter, and the mounting pipe that extends to each home beyond, the junction angle is sharp, including the joint, but it is tens of hearts Inexpensive fiber optic and tape cores are sufficient, but in order to lay them in sewer pipes, they exhibit chemical resistance (mainly acid resistance), and bend or damage when laying. Core fiber (optical fiber) even in poor environment without giving
Since it is necessary to develop a protection pipe capable of protecting the water, a study was conducted.

[0005]

As a result of the study, what has been developed is a protective pipe for a chemical resistant optical fiber core. In the melted polyolefin resin, the multifilament fiber is impregnated with the resin, pulled out from a round nozzle with an opening, and cooled and molded, reinforcing it with unidirectional fibers in the polyolefin resin matrix. A pipe-shaped object (FIG. 1) was obtained. The pipe was filled with the optical fiber core by inserting the optical fiber core from the opening and sliding the pipe-like object without applying tension to the optical fiber core, and welding the opening.

The multifilament fibers impregnated with resin have high tensile strength, tensile modulus and heat resistance.
Aramid fiber or PBO fiber with low elongation can be used. In addition, as a preferable resin, a thermoplastic resin such as polypropylene or polyethylene having excellent chemical resistance can be used. Since this shape can sufficiently withstand pulling at the time of laying and has flexibility, it is 90 degrees. The optical fiber can be bent at an angle that does not damage the optical fiber without bending the resin.

However, in order to lay a long pipe while sliding, abrasion resistance is required, so that the pipe can be used as a core and tied with a braid.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view in which a braid is covered on a protection pipe for a chemical resistant optical fiber core having a core core of a two-core tape to which the present invention is applied.

In the protective pipe for chemical-resistant optical fibers according to the present invention, it is necessary to easily insert the optical fiber into the outer pipe at the time of forming the pipe. It is melted at a temperature and impregnated with a multifilament fiber (for example, Zylon (registered trademark, manufactured by Toyobo Co., Ltd.)) obtained by liquid crystal spinning polyparaphenylene benzobisoxazole (PBO). By pulling out from the nozzle and cooling, a pipe-shaped molded product having an opening can be obtained.

[0010] Further, while inserting the optical fiber core wire into the pipe-shaped object having the opening, the opening of the pipe is heated and melted by a roll-shaped heater (Fig. 4) and passed through a cooling roll to be continuous. An optical fiber core can be inserted into a pipe.

The chemical-resistant optical fiber core protection pipe is a pipe reinforced with unidirectional fibers, has a high tensile strength, and has low physical shock, bending, or chemical resistance to the optical fiber core. It can be given to.

[0012]

【Example】

EXAMPLE 1 The mechanical strength (tensile strength), environmental resistance (chemical resistance), and communication characteristics of a protective pipe for a chemical resistant optical fiber core wire according to the present invention were measured with the optical fiber core wire inserted. . As the polyethylene resin used for pipe making, a linear low-density polyethylene was heated and melted at 180 degrees Celsius to obtain a multifilament fiber (1,110 d tex 4) of Zylon (registered trademark, manufactured by Toyobo Co., Ltd.).
After pulling out this book from a round nozzle with an opening through an impregnating roll (Fig. 2) and cooling and hardening, an optical fiber core wire is inserted into the opposite side of the opening, and the opening is opened in a state where heat is not easily applied. After heat-welding at a temperature of 180 degrees Celsius with a heat roll, it was cooled with cold air to produce a pipe containing an optical fiber core wire having an inner diameter of 3.5 mm and an outer diameter of 4.8 mm.

[0013] As a tensile strength test, 98.
When communication was attempted while pulling from both ends with a force of 0N, there was no effect on the communication. Next, as an environmental test, the specimen was immersed in sulfuric acid having a concentration of 5% or 10% shown in Table 1 at room temperature for 28 days. Thereafter, the tensile strength test was conducted. No effect.

Further, assuming that the transparent resin pipe having a diameter of 150 mm and a length of 1 m is connected to a transparent resin pipe having a diameter of 250 mm and a length of 2 m at a right angle, assuming that the pipe is inserted into the sewer pipe, it is regarded as a sewer pipe and is laid and installed in a real environment. I tried to communicate below.
The laying method is as follows. The cable for pulling out is passed beforehand, and the protection pipe for the chemical resistant optical fiber core wire is 50 m at the tip.
It was tied, pulled out, and inserted, but it was confirmed that the vehicle passed without any breakage of the resin at the orthogonal portion, the bend angle did not become 40R or less, and there was no hindrance to communication at all.

[0015]

[Comparative example]

[Comparative Example 1] A communication test is performed by passing each of [1] optical fiber core wire, [2] core tape core wire, and [3] two-core optical cord, which are generally sold, through a tube bent at 90 degrees as described above. [1], [2], and [3]
It broke and communication became impossible.

[0016]

The protective pipe for chemical-resistant optical fiber of the present invention can be used in a sewer pipe or an installation pipe that cannot be directly operated by a worker. It can cover stress such as compression and chemical resistance, and can guarantee stable communication for a long time.

[Brief description of the drawings]

FIG. 1 is a perspective view of a protection pipe for a chemical resistant optical fiber core wire to which the present invention is applied.

FIG. 2 Resin impregnated part

FIG. 3 is a perspective view of a protection pipe for a chemically resistant optical fiber core wire having a honeycomb shape.

FIG. 4 Welded part of pipe

FIG. 5 is a nozzle section

[Explanation of symbols]

 (1) Optical fiber core or tape core (2) Polyethylene resin (3) Multifilament fiber (4) Rib (5) Joint (6) Nozzle (7) Resin impregnated roll (8) Take-up roll (9) Heater (10) Heat roll (11) Holder roll (12) Round (13) With round rib (14) Honeycomb shape (15) With honeycomb shape rib

Continued on the front page (72) Inventor Mitsuo Ozaki 3-19-26 Minamiki, Okayama-shi, Okayama Pref. Misaki Gumi Co., Ltd. (72) Inventor Makoto Annobu 566-1, Kurosaki, Kurashiki-shi, Okayama Pref. Takao Shoji F Term (reference) 2H038 CA68 2H050 BC11 BC17 BD00

Claims (3)

[Claims] 1. A multifilament fiber having a tensile strength of 15 cN / dtex or more and an elastic modulus of 400 cN / dtex.
As described above, a protective pipe for a chemical-resistant optical fiber core wire, which has a performance of a breaking elongation of 6% or less and is arranged in one direction in a polyolefin resin. 2. The protection pipe according to claim 1, further comprising a linear reinforcing rib on the outside of the pipe in the same direction as the fiber direction. 3. The protective pipe according to claim 1, wherein the outside of the pipe is covered with a braid of multifilament fibers.